The University of Pittsburgh AsthmaNet proposal includes 3 protocols, with a 4th mechanistic protocol built around unmet asthma needs and phenotyping. These protocols should contribute to understanding asthma phenotypes in relation to mechanisms and specific treatment, particularly in relation to health disparities and contributions from race, socioeconomic status (SES) and asthma severity. These protocols build on our inherent expertise in asthma phenotyping and biology, racial/ethnic/socioeconomic issues, environmental effects, particularly in relation to underserved populations, psychosocial stress, and severe asthma. Our proposal includes participation from the Center for Minority Health with expertise in outreach in minority populations, a partner at Rainbow Babies of Case Western Reserve and a satellite at Allegheny General Hospital in Pittsburgh. The 1st clinical trial will compare two approved drugs for treatment of the adult onset asthma phenotype, which hypothesizes that a 5-lipoxygenase inhibitor will be more effective than a leukotriene receptor antagonist. The 2nd study evaluates the role of race in relation to SES on corticosteroid (CS) responses in children, h3TJ0thesizing that the African-American asthma phenotype, with and without regard to SES, predicts a poor response to inhaled CSs in asthmatic children. Vitamin D supplementation will overcome the poor response and improve outcomes. We will recruit African American and Caucasian children stratified by race and SES. Children who remain symptomatic following initial stabilization will be treated with high dose ICS and response determined. Children of all groups who do not improve will be randomized to treatment with Vitamin D or higher ICS dose to determine whether Vitamin D + lower dose ICS improves exacerbations and CS responsiveness better or to the same degree than the higher dose ICS. The mechanistic ancillary protocol will address whether aspects of CS unresponsiveness can be modeled in vitro, including effects of race/SES factors on cytokine suppression and histones, and the effect of Vitamin D to improve them. Finally, the severe asthma protocol will focus on the mast cell, specifically prostaglandin D2 and its interaction with CRTH2. We believe these studies address unmet needs in asthma and will improve its therapy.